Systems and methods for spinal fixation

ABSTRACT

Featured are a method and apparatus for fixing adjacent vertebrate of a spine that avoids the need and associated problems with prior cage or straight rod and screw systems. Methods and apparatus of the invention utilize a new implant member, which preferably is arcuate. Preferred methods of the invention for stabilizing adjacent vertebrae of the spine, include steps of providing a positioning apparatus including two guide sleeves, each guide sleeve having a long axis and locating the two guide sleeves with respect to the adjacent vertebrae such that a vertex formed by the long axis of each guide sleeve is located in the intervertebral space for the adjacent vertebrae. The method further includes forming an aperture in each of the adjacent vertebrae using the guide sleeves and inserting an implant into the apertures formed in each of the adjacent vertebrae so that the implant extends between the adjacent vertebrae and through the intervertebral space. In an alternative method a cutting fixture including a pivot arm is secured to the adjacent vertebrae and a cutting device is secured to the pivot arm. The pivot arm and cutting device are configured and arranged so that rotation of the pivot arm about a particularly located pivot point allows the cutting device to form the aperture in each of the adjacent vertebrae. Another alternative method for fixing adjacent vertebrate of a spine includes the step of forming a common channel in and between the adjacent vertebrae and inserting a biscuit implant in the common so as to bridge between the adjacent vertebrae.

This application claims the benefit of U.S. Provisional Application Ser.No. 60/133,356 filed May 10, 1999, and of U.S. application Ser. No.09/536,732, filed Mar. 28, 2000, which applications are incorporatedherein by reference in their emtirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to methods, systems andapparatuses for bony fixation, more particularly to methods, systems andapparatuses adapted for fixing the bones of the spine, and to methods,systems and apparatuses adapted for securing a prosthetic device withinthe bones of the human body, more specifically securing a prostheticdevice within the bones of the spine.

2. Background of the Invention

Fixation or fusion of vertebral columns with bone or material, rods orplates is a common, long practiced surgical method for treating avariety of conditions. Many of the existing procedures involve the useof components that protrude outwardly, which may contact and damage abody part, such as the aorta, the vena cava, the sympathetic nerves, thelungs, the esophagus, the intestine and the ureter. Also, manyconstructions involve components that may loosen and cause undesirableproblems, often necessitating further surgical intervention.Additionally, limiting the success of these procedures are thebio-mechanical features of the spine itself, whose structure mustsimultaneously provide support to regions of the body, protect thevertebral nervous system and permit motion in multiple planes.

As indicated above, spinal surgery for spine fusion generally involvesusing implants and instrumentation to provide support to the affectedarea of the spine while allowing the bones thereof to fuse. Thetechnology initially evolved using bone chips around and on top of anarea of the spine that had been roughened to simulate a fracture in itsconsistency. The area, having encountered the bone chips, would thenproceed to heal like a fracture, incorporating the bone chips. However,surgical procedures dealing with the spine present notable challenges.For example, bioengineers have been required to identify the variouselements of the complex motions that the spine performs, and thecomponents of the complex forces it bears. This complexity has made itdifficult to achieve adequate stability and effective healing insurgical procedures directed to the spine.

One surgical technique provided by Cloward, involves cutting a doweltype hole with a saw across or through the moveable intervertebral discand replacing it with a bone graft that was harvested from the hip bone.This procedure limits motion and mobility and results in a fusion of theadjacent vertebral bodies. However, as a result of the complex motionsof the spine, it is often difficult to secure the dowel from displacing.Further, it has become apparent over time, however, that this particulartechnique does not always yield a secure fusion.

Other techniques have been developed that involve the placement ofvarious hardware elements, including rods and hooks, rods and screws andplates and screws. The dowel technique also has advanced over the pastfive years or so, with dowels being fabricated from cadaver bone ormetals such as titanium or stainless steel. These techniques, whetherusing hardware, dowels or some combination thereof, have a common goalto enhance stability by diminishing movement, thereby resulting in orenhancing the potential of a fusion of adjacent vertebral bones. Forexample, in one of these other techniques, the disc is removed andadjacent vertebrae are positioned in a stable position by placing aplate against and traversing them, which plate is secured or anchored toeach by means of screws.

In another procedure, cages in the form of two parallel circular orrectangular devices are made out of a material such as titanium orstainless steel and these devices are fenestrated. Bone is packed in thecenter of the devices that will heal to adjacent bone through eachfenestration. In this procedure, the disc space is distracted so allligamentous structures are taut and the bones are held in their normalmaximal position of distraction. Because the cages are implanted inspongy bone, they are more likely to collapse the surrounding bone, thusresulting in loss of distraction and subsequently cage dislodgment.

U.S. Pat. No. 5,591,235 reports a certain spinal fixation device andtechnique for stabilizing vertebrae. In this technique, a hollow screwis inserted into a hole, preferably a hole saw recess, in each adjoiningvertebrae. A channel is cut into the vertebrae, which is lined up withcorresponding axial slots in the screw. A rod is inserted into thechannel and so as to pass through the axial slots in the screw. The rodis secured to each of the screws by means of a locking cap. The rod alsois arranged so as to provide a bridge between the hollow screws in theadjoining vertebrae. Certain disadvantages have been surmised using sucha device and technique. For example, it has become apparent that thetrough in the vertebral bodies destabilizes some of the cortex of thevertebrae body wall, which is the strongest component.

In addition to fixation or fusion of vertebral columns, the prior artalso describes methods or other spinal repair procedures, such asdiscectomy wherein an artificial disc or prosthetic device is placedwithin the vertebrae of the spine. For such prior art methods andrelated devices, there have been short comings such as having difficultyin securing the prostheses within the vertebral space or resulting insignificant modification or damage to the load bearing surfaces of thevertebrae in an effort to secure the prosthesis.

Thus, it would be desirable to provide a new apparatus, system andmethods for spinal fixation that enhances healing of the bone whileproviding structural support to the spine. It would be particularlydesirable to provide such an apparatus, system and method that wouldinvolve the use of open surgical or minimally invasive surgicaltechniques as well as a technique in which the implant burrows in thebone spine, traverses across the disk space, and ends in an adjacent orneighboring vertebrae or vertebras, providing limited or no protrusions.It also would be desirable to provide such an apparatus, system andmethod where the implant is retained within the bone without requiringcontour-varying external vertebral wall fixation as compared toconventional devices, as such a device would avoid many of the problemsassociated with conventional devices such as blood vessel injury,erosion into organs, as well as placement near nerves. Additionally, itwould be desirable to provide such an apparatus, system and method wherethe implant is retained within the bone and is utilized to secure anartificial prosthesis for example within the vertebral bodies. Suchsecuring is accomplished with or without the use of the annulus, andwithout insult to portions of the vertebral surfaces bearing significantloading.

SUMMARY OF THE INVENTION

I have now found new methods and apparatus for fixing adjacentvertebrate of a spine. The methods and apparatus of the inventionutilize a new implant member, which preferably is arcuate, and avoidsthe associated problems with prior cage or straight rod and screwsystems. It is within the scope of the present invention for the implantmember to have any geometric shape or configuration consistent with theintended use including a straight member.

Preferred methods of the invention for stabilizing adjacent vertebrae ofthe spine, include the steps of providing a positioning apparatusincluding two guide sleeves, each guide sleeve having a long axis andlocating the two guide sleeves with respect to the adjacent vertebraesuch that a vertex formed by the long axis of each guide sleeve islocated in the intervertebral space for the adjacent vertebrae. Themethod further includes forming an aperture in each of the adjacentvertebrae using the guide sleeves and inserting an implant into theapertures formed in each of the adjacent vertebrae so that the implantextends between the adjacent vertebrae and through the intervertebralspace.

Preferably, the aperture formed in the vertebrae is arcuate and theimplant being inserted also is arcuate. The arcuate aperture in eachvertebrate can be suitably formed by drilling or other ablation. Moreparticularly, an initial aperture can be drilled in each of the adjacentvertebrae to create intersecting apertures with convergent paths withinthe intervertebral space; and the initial aperture then enlarged toreceive the implant. That enlarging of the initial aperture can besuitably performed by a variety of procedures, e.g. by using a drillbit, a reamer, an awl, impaction drill, shape memory coring device, orcurved coring device, or the like.

The step of forming an aperture also can further include inserting aguide member, after drilling of the initial aperture, into one of theguide sleeves, down through the initial aperture in one adjacentvertebrae, through the intervertebral space and into the initialaperture in the other adjacent vertebrae; and advancing an apertureenlarging device over the guide member so as to enlarge the initialaperture. In this case, the aperture enlarging device is suitably acurved reamer or a curved drill bit, and the curved reamer or the curveddrill bit is advanced over the guide member so as to form an arcuateaperture in each of the adjacent vertebrae. It also should beappreciated that multiple vertebral holes can be created using the samemethods as disclosed herein. In that manner, multiple arcuate implantscan be placed, e.g. if greater mechanical stability is considereddesirable.

The positioning apparatus can further include a cross member and anintervertebral spacer, preferably where the guide sleeves are pivotallymounted to the cross member and the intervertebral spacer is spaced fromthe cross member and interconnected thereto at about a mid point betweenthe pivot points for the guide sleeves. In this case, the stabilizingmethod can further include locating the intervertebral spacer in theintervertebral space between the adjacent vertebrae; and maintainingalignment of the guide sleeves with respect to the adjacent vertebrae sothat a consistent angle is maintained between the guide sleeve and thevertebrae during at least a portion of said forming of the aperture. Theintervertebral spacer also can be configured so as to provide protectionto the spine during the drilling when disposed in the intervertebralspace.

In an alternative embodiment, the positioning system being providedincludes a cutter bracket system and a curved drilling sub-systemaffixed thereto. The cutter bracket system includes a pivot arm whosepivot point is disposed between the adjacent vertebrae opposite theintervertebral space. More particularly, the pivot point is at about themidpoint between the adjacent vertebrae. The curved drilling sub-systemis affixed to the pivot arm such that as the pivot arm rotates about thepivot point the curved drill sub-system follows an established cuttingpath. In a more specific embodiment, the drilling sub-system is affixedproximal or at the distal end of the pivot arm. The positioningapparatus according to the alternative embodiment can further include amechanism that temporarily secures the cutter bracket system to theadjacent vertebra to be fused and which positions and maintains thepivot point at the desired location. Also, the curved drill subsystemcan include a curved cannula, a flexible member running through thecurved cannula and a cutting burr secured to an end of the flexiblemember.

As to the step of forming an aperture using a positioning systemaccording to the alternative embodiment, this step includes rotating thepivot arm in one direction about the pivot point so the curved drillingsub-system forms an aperture in one of the adjacent vertebrae androtating the pivot arm in another direction about the pivot point so asto form an aperture in the other of the adjacent vertebrae. In a morespecific embodiment, the step of forming further includes remounting thecurved drilling subsystem to the pivot arm before rotating the pivot armin the another direction so a cutting element of the curved drillingsubsystem is aligned for the direction of movement.

As to inserting the implant, the method step includes successivelydrawing a portion of the implant through the arcuate aperture in oneadjacent vertebrae, through the intervertebral space and into thearcuate aperture of the other adjacent vertebrae. In a specificembodiment, the step of inserting includes securing one end of a guidewire to an end of the implant; passing a free end of the guide wirethrough the arcuate aperture in one of the adjacent vertebrae, throughthe intravertebral space and through the arcuate aperture in the otheradjacent vertebrae; and pulling on the guide wire free end to therebysuccessively draw the portion of the implant.

In another embodiment, the step of inserting includes inserting abeginning end of the implant into an entrance opening of one of theadjacent vertebrae; applying a force to the portion of the implantextending from the entrance opening so as to drive the implant beginningend though the arcuate aperture in the aperture of said one of theadjacent vertebrae, through the intervertebral space and into thearcuate aperture in the other of the adjacent vertebrae.

The implant being inserted into the final aperture is made from one ormore of a metal (e.g., titanium or stainless steel), bone, morphogenicprotein (including a combination of bone and bone morphogenic protein),carbon fiber composite, nitinol or biodegradable materials such aspolyactic acid or polyglycolic acids and copolymers and otherderviatives thereof, or collagen and collagen coated metal or bone. Theimplant also may comprise an in situ-formed plug where the aperture actsas a mold for an epoxy or other polymer-based system. Also, the implantcan be solid or hollow and arranged with or without ingrowthfenestrations and screw holes for post-insertion securement. The implantalso can be configured so the implant includes a first and a secondsection, where a distal end of each of the first and second sections isconfigured so as to be capable of being secured together. For such animplant, the method further includes the steps of inserting the firstsection into the aperture in one of the adjacent vertebrae so that thedistal end therefore is disposed in the intervertebral space; insertingthe implant second section into the aperture in one of the adjacentvertebrae so that the distal end therefore is disposed in theintervertebral space; and securing the distal ends of the first andsecond sections together. The implant sections being inserted can bearcuate with a radius substantially the same as the arcuate aperture orsubstantially straight. In particular embodiments, the distal ends ofthe implant sections are secured to each other by e.g. a nut, bolt, pin,expansion or press-fit device, or interlocking member on the end of eachsection. Other stabilization methods also can be employed. For instance,a plate can be applied to the vertrebrae surface with attachments ateach end of the tunnel traversed by an implant in accordance with theinvention.

Another method of the present invention for stabilizing adjacentvertebrae of the spine includes the step of forming a common channel inand between the adjacent vertebrae and inserting a biscuit implant inthe common channel so as to bridge between the adjacent vertebrae. Inmore specific embodiments, the step of forming includes simultaneouslycutting a slot, preferably an arcuate slot, in each of the adjacentvertebrae so as to form the common channel and providing a deviceconfigured so as to be capable of simultaneously cutting the slot ineach of the adjacent vertebrae. Also for said step of inserting, thebiscuit implant can be further configured so as to include a spacerelement that is received in the intervertebral space between theadjacent vertebrae when the biscuit is disposed in the common channel.

In another alternative aspect of the invention, a diskectomy can beperformed and a stabilizing wedge (inner) implant inserted between thevertebrae. The wedge (inner tool) establishes lordosis, provides aconstruction reference, and carries on it the stabilizing wedge implant.Retracted stop-cut blades on the inner tool are then engaged, cuttinginto the vertebrae in the vertical plane. A hole saw can be used tocreate a circular cut in the vertebrae to facilitate insertion of theouter implant. Once the cut is complete, the bone harvested in thetubular cutter can be manipulated into the implant. A circular (outer)implant is then inserted over the inner tool. The outer tool thenreferences the position of the inner tool and guides the implant intoplace. After the two implants nest together along a key and groove, theouter tool is removed. A fenestrated circular member then replaces theouter cutting tool and the inner tool is rotated about 90 degrees andthen removed. Working together, the two rotated implants capture thevertebral body sections, which are now rotated about 90 degrees andthrough their many holes, provide blood exchange with the adjacent boneto accomplish fusion.

Also featured is a system and apparatus embodying the described methodsor techniques for internal fixation of the spine.

Other aspects and embodiments of the invention are discussed below.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1A is a schematic view of a positioning jig according to thepresent invention;

FIG. 1B is a front view of the intervertebral spacing member of FIG. 1A;

FIG. 2A is a schematic view of the positioning jig of FIG. 1A disposedabout two vertebral bodies;

FIG. 2B is a schematic view of an alternative positioning jig accordingto the present invention disposed about two vertebral bodies;

FIGS. 3A–E are schematic views that illustrate the various steps of theprocess to form a hole in each vertebral body for implanting a fixatingmember therein;

FIGS. 4A and 4B are schematic views that illustrate alternate ways ofmaking a hole in each vertebral body;

FIG. 4C is a plan view of a Romano device for making a curved hole.Shown is one of the two opposed curved cutter guides and a flexiblecable having a cutting bit attached to one end;

FIG. 5A is a schematic view of one device for implanting the fixatingmember;

FIG. 5B is a schematic view of alternate device for implanting thefixating member;

FIG. 6A is a schematic view of the vertebral bodies illustrating theimplantation of the fixating member in the holes;

FIG. 6B is a schematic view of the vertebral bodies illustrating anotherform of implantation of the fixating member in the holes particularlyfor securing an intravertebral prosthetic device;

FIG. 6C is a schematic view of the vertebral bodies to illustratesecuring of the fixating member;

FIGS. 7A–C are schematic views of the implantation of a fixating membermade from nitinol;

FIGS. 8A–B are exemplary cross sectional views of a guide sleeveincluding a mechanical guide to guide the nitinol fixating member duringinsertion;

FIG. 9 is a schematic view of the vertebral bodies with a fixatingmember according to a second aspect of the present invention;

FIG. 10 is a schematic view of the vertebral bodies with a fixatingmember according to a third aspect of the present invention;

FIG. 11A is a schematic view of a cutter bracket system according to thepresent invention;

FIG. 11B is a schematic view of a curved drill used with the cutterbracket system of FIG. 11A;

FIG. 12A is a perspective view of a common channel cutting deviceaccording to the present invention;

FIG. 12B is a perspective view of a portion of the channel cuttingdevice of FIG. 12A with the cutting implement extended;

FIG. 12C is a schematic view of the channel cutting device of FIG. 12Adisposed on two vertebral bodies;

FIG. 12D is a schematic view of the two vertebral bodies to illustratethe implantation of the biscuit implant in the cut common channel;

FIG. 12E is another view of the two vertebral bodies to illustrate theimplantation of the biscuit implant including a spacing element in thecut common channel;

FIG. 12F is a perspective view of the biscuit implant of FIG. 12D;

FIG. 12G is a side view of the biscuit implant with spacing element ofFIG. 12E;

FIGS. 12H–K are perspective views of various exemplary biscuit implantsaccording to the present invention;

FIGS. 13A–13F illustrate an alternative implant system of the invention;where FIG. 13A is an isometric view of an inner implant, FIG. 13B is anisometric view of an outer implant, FIG. 13C is a lateral view showing apreferred positioning of the implant system, FIG. 13D is an anteriorview of the outer implant within which the inner implant is secured,FIG. 13F is an anterior view of the outer and inner implant afterrotation, and FIG. 13F is a perspective view of an embodiment of theimplant system;

FIG. 14A is a schematic view of an inner tool positioned within theintervertebral disk space;

FIG. 14B is an isomeric view of the inner tool;

FIG. 14C is a cross-sectional view of the inner tool, with retracted andextended stop-cut blades;

FIG. 15 is a schematic view of the inner and outer tool systempositioned in relation to the vertebral bodies;

FIG. 16 is a schematic view showing bone-to-bone with no gapapplication; and

FIGS. 17A–C are schematic views of exemplary implants useable forsecuring a prosthetic device.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the various figures of the drawing wherein likereference characters refer to like parts, there is shown in FIGS. 1–2various schematic views of a drill guide or positioning jig 100 thatpositions or aligns the drill bits before making the holes in each ofthe vertebral bodies 2. The positioning jig 100 includes two guidesleeves 102, a cross member 104 and an intervertebral spacing member110. Each guide sleeve 102 preferably is a hollow tubular member havinga lumen or passage therein for receiving and guiding the means forforming at least the initial aperture in the adjacent vertebrae such asa drill bit 150 (FIG. 3B). As indicated elsewhere herein, the aperturemay be formed using other techniques such as the ablation of bone by anenergy source, e.g., high-pressure water, high-pressure air, ultrasound,or a laser. As such, it shall be understood that the internal sizing andconfiguration of the guide sleeves is established to accommodate theparticular mechanism used for forming the aperture.

The guide sleeves 102 are mounted to the cross member 104 in such a waythat they are each pivotal about the cross member and so each can besecured or locked in a particular angular position with respect to thecross member. Although a single mounting/pivot point 106 is illustrated,it is within the scope of the present invention for the cross member 104and each guide sleeve 102 to be configured with a plurality or more ofsuch pivot/mounting points. In an exemplary embodiment, the cross member104 and guide sleeves 102 are constructed from stainless steel; and eachguide sleeve is pivotally secured to the cross member by screws.

The distal end 108 of each guide sleeve 102 is configured formechanically engaging a surface, edge, corner or other surface artifactor feature of the vertebral body 2. In an exemplary embodiment, and asmore clearly illustrated in FIG. 3A, the guide sleeve distal end 108 isconfigured or arranged with a cutout that is designed to accept thecorner of the vertebral body 2. Additionally, the cutout area and thusthe distal end 108 also are configured with a plurality or more of teeth107. The teeth 107 are configured and arranged so the teeth bite intothe bony surface of the vertebral body when the corner of the vertebralbody 2 is received within the cutout area of the guide sleeve distal end108. Each guide sleeve is suitable about 20 cm in length, althoughsuitable and preferred guide sleeve lengths can vary depending on themethod of access.

The intervertebral spacing member 110 includes an intervertebral spacer112 and an interconnecting member 114 that mechanically interconnectsthe cross member 104 and the intervertebral spacer 112. Theinterconnecting member 114 is secured to or retained by the cross member104 so as to be maintained in fixed relation with respect to the pivots106 for both guide sleeves 102. In an exemplary embodiment, theinterconnecting member 114 is located at about the midpoint of the crossmember 104 between the pivots 106. The interconnecting member 114 alsois secured to the cross member 104 so the intervertebral spacer 112 ispositioned between the distal ends 108 of the guide sleeves 102. Moreparticularly, the interconnecting member 114 is positioned so theintervertebral spacer 112 is received within the distended disc spacebetween the adjacent vertebral bodies 2.

In an exemplary embodiment, the interconnecting member 114 is in theform of a rod and the cross member 104 is configured with a throughaperture 109 in which the rod is received. This configuration provides amechanism by which the interconnecting member 114 is put into andmaintained in fixed relation with respect to the pivot points 106. It iswithin the scope of the present invention for the cross member 104 tohave any geometric shape, as well as being hollow or solid inconstruction, that is otherwise consistent for the intended use of thepositioning jig 100.

The interconnecting member 114 also can be configured so as to preventrotational motion of the interconnecting member with respect to thethrough aperture 109. For example, the rod and through aperture 109 maybe configured so as to include a flat side in a portion of thecircumference for the through aperture and the rod. Alternatively, thethrough aperture and rod may be arranged with a key and notcharrangement to prevent rotation.

When the guide sleeves 102 are secured to the cross member 104 and eachguide sleeve distal end 108 mechanically engages the surface of thevertebral body 2, the guide sleeves are arranged so they maintain aconsistent angle with respect to the vertebral body. Additionally, andin combination with the intervertebral spacer 112, this arrangementprovides a three-point reference that ensures appropriate angles andalignment are maintained. Additionally, such a configuration establishesa condition whereby the positioning jig 100 locks down on the motionsegment of the spine to be stabilized.

The use of the positioning jig 100 in the method of the presentinvention can be understood from the following discussion with referenceto FIGS. 1–6. It shall be understood that as preparation for spinalfixation/stabilization, the medical personnel (e.g., surgeon) obtainsaccess to the motion segment or structures to be stabilized or fusedusing any of a number medical/surgical procedures known to those skilledin the art. In this regard, this would involve such actions as preparingthe disc space and performing retraction of vessels, muscles and nerves.

In this regard, it should be recognized that the method and positioningjig 100 of the present invention are particularly advantageous whenperforming a minimally invasive surgical procedure. The minimallyinvasive procedure can be performed through three holes, each about 1inch across, in the abdomen and allows for the procedure to be executedwithout visualizing the vertebrae. Thus, and in contrast to a number ofprior procedures, methods of the invention are not limited to ananterior presentation. Such methods of the invention also can beperformed through a posterior, posteriolateral or pedicular approach.

In addition, when using a nitinol implant, the positioning jig 100allows the implant to be properly positioned for and during insertionthereof. After gaining access, the surgeon also could scrape out thematerial from the failed disc or use this disc or its space as areference point.

As preparation, the surgical personnel also select an intervertebralspacing member 110 that is appropriately sized, so it can accommodatethe distended disc space. The intervertebral spacer 112 portion of theintervertebral spacing member 110 is inserted into the intervertebralspace 4 between the adjacent vertebrae. In this way, the approximatecenter or mid point of, and the staring point on, the adjacent vertebraeto be fused or stabilized is thereby established or defined.

The intervertebral spacer allows the surgeon to maintain extremelyaccurate disk spacing. The intervertebral spacer also protects thespinal cord from accidental drilling or boring. If desired, the spacercan be made of bone and can be made with or without a through hole. Thespacer design is suitably based on a construction that facilitates theselected technique for creating an arcuate aperture. An intervertebralspacer that is comprised of bone offers the advantage of being able toremain implanted following the procedure.

Other materials also can be suitably employed to form an intervertebralspacer. The placement of an implant provides a central axis throughwhich a compressible, functional intervertebral disk member can bereliably secured. The artificial disk member suitably can be made from avariety of compressible materials, including e.g. silicon, elastomericpolymers, polyurethanes and copolymers thereof, hydrogels, collagen orbioabsorbables.

Next, the positioning jig 100 is locked down on top of the motionsegment to be immobilized, as more clearly shown in FIG. 2. In thisregard, the surgical personnel slide the interconnecting member 114 ofthe intervertebral spacing member 1110 into an aperture 109 provided inthe cross member 104. In this way, the aperture 109 in the cross member104 positions the intervertebral spacing member 110 between the distaland proximal ends of the drilling guides 102. Although illustrated asbeing located in the mid-point, the intervertebral spacing member can becentrally located or offset to either side to enable drilling of holesin the vertebrae laterally against the spine.

Preferably, the aperture 109 in the cross member 104 is configured so asto prevent the cross member 104 or intervertebral spacing member 110from rotating with respect to each other. For example, a portion of theaperture 109 and a portion of the interconnecting member 114 isflattened so as to pre-define a given orientation. Alternatively, theaperture 109 is configured with a notch or keyway and theinterconnecting member 114 is configured with a key or protrusion thatis received in the keyway.

As provided above, the distal end 108 of each guide sleeve 102 ispreferably configured so each distal end mechanically engages thesurface of the vertebrae 2. In the illustrated embodiment, the distalend 108 is arranged with a cutout area that is designed to accept thecorner of the vertebrae 2 as more clearly illustrated in FIG. 3. As alsoshown in FIG. 3, the cutout area is provided with a plurality of teeth107 that bite into the bony surface of the vertebrae 2. It is within thescope of the present invention for the guide sleeve distal end 108 to bedisposed at other positions on the surface of the vertebrae 2 such asthat illustrated in FIG. 6A.

After locating the positioning jig 100 with respect to the motionsegment to be fused, the surgical personnel secure the guide sleeves 102at each of the pivots 106. This advantageously ensures that theappropriate angles and alignment of the guide sleeves 102 with respectto the vertebrae 2 are maintained as well as locking the positioning jig100 down on the motion segment to be fused.

As noted above, an initial through hole is formed in each vertebrae 2 byany of a number of methods, e.g. by a drill, by ablation of the materialcomprising the vertebrae using an energy source such as RF, ultrasonicwaves, cryogenics and water jets or by any other means known to thoseskilled in the art and which can be adapted for use with the positioningjig 100 of the present invention. For purposes of describing the presentinvention, however, the following discussion is simplified to describingthe method in terms of drilling the initial aperture or initial throughhole 6 in the vertebrae 2. This, however, shall not be inferred as beinga limitation on the method according to the present invention to onlydrilling.

A fixed or flexible drill bit 150 is inserted into and down each drillguide 102 so the ends thereof contact the surface of the vertebrae 2.The surgical personnel operate the drill bits in accordance withaccepted techniques so as to create an initial through hole 6 in each ofthe vertebrae. Preferably, and as shown in FIG. 3B, the through holes 6being created are intersecting with convergent paths within theintervertebral space 4. In other words, the projection of the long axisfor each of these through holes 6 intersects so the vertex created byintersection of the long axes is located within the intervertebral space4.

The initial through hole 6 initially formed in each vertebrae 2 has adiameter much less than that of the implant 160 that is to be used tostabilize or fuse the motion segment. After forming the initial throughhole 6, the surgical personnel insert a guide wire 170, such as a 0.093inch nitinol guide wire, into and down one guide sleeve 102 and throughthe through hole in one vertebrae 2. The surgical personnel continue topush the guide wire 170 across the intervertebral space 4 and into thethrough hole 6 in the other vertebrae as more clearly illustrated inFIGS. 3C–D. In a particular embodiment, the guide wire 170 is configuredwith a slightly curved tip. The guide wire 170 is generally in a curvedconfiguration when disposed in the through hole 6 of the vertebrae 2.

A flexible/curved drill bit 152 is then passed through one of the guidesleeves 102 and over the guide wire 170 so as to form a curved throughaperture 6 a in each of the vertebrae as shown in FIG. 3E. The curved orarcuate through aperture 6 a is formed with a cross-section thatcomplements the cross-sectional shape of the implant 160. Preferably,the arcuate through aperture is sized to be slightly smaller than thatof the implant 160 so there is a friction, snug or interference fitbetween the implant 160 and the arcuate through aperture 6 a.

In this way, when the implant 160 is inserted into the arcuate throughaperture 6 a, it will remain therein without further need of screws orother artifacts or devices for securing the ends of the implant to eachvertebrae 2. It is within the scope of the present invention, however,for screws or other devices be provided as an additional measure orprotection for securing the implant 160 within the vertebrae 2.

Alternatively, the curved or arcuate through aperture 6 a is formedusing any of a number of other techniques as described below. In onecase, and as shown in FIG. 4A, the arcuate through aperture 6 a isformed in the vertebrae 2 by using a flexible reamer 200. The flexiblereamer is run or passed over the guide wire 170 to ream or core out thearcuate through aperture 6 a. The cancellous bone of the vertebrae 2 isrelatively soft so that it is possible to use a reamer to core the holeaperture. Similarly, and as shown in FIG. 4B, a curved awl or aprogressively larger guide wire 170 a can be used to punch a curved holein the vertebrae. FIG. 4C shows a Romano device suitable for drilling acurved bore such as that disclosed in U.S. Pat. No. 5,700,265 theteachings of which are incorporated herein by reference. A swing arm 830and curved guide arm 834 navigate the drill bit 840 through a definedradius of curvature.

In addition to the mechanical devices for drilling, punching or reamingout the arcuate through aperture 6 a, the discharge end of an energysource, such as RF, ultrasonic, cryogenic, laser and water, can belocated within the guide sleeve 102 and passed over the guide wire so asto form the arcuate through aperture. For example, the nozzle(s) of ahigh pressure water source can be arranged so the discharging or icecrystal water impinges on the bony material of the vertebrae 2 and thematerial is thereby ablated away to form the arcuate through aperture 6a. Similarly, laser light, RF waves or ultrasonic waves can be focusedon the bony material within the vertebrae 2 to form the arcuate throughaperture 6 a.

The foregoing describes the formation of the arcuate through aperture 6a that receives the implant 160 by passing a mechanism from the entranceto the exit of the initially formed through hole 6. It is within thescope of the present invention, for a guide to be located within theintervertebral space 4 so the curved through aperture is formed bydrilling from the intervertebral space out, rather from the outside in.

There is shown in FIG. 2B a schematic view of an alternative positioningjig 100 a that is disposed about two vertebral bodies. This alternativepositioning jig 100 a is similar to the positioning jig 100 of FIG. 2Aexcept for the guide sleeves. As such reference shall be made to theforegoing discussion regarding FIGS. 1–2A for further details as to thecommon features for these two positioning jigs 100, 100 a. In theillustrated embodiment, a guide wire 170 is being inserted into one ofthe guide sleeves 102 a and is configured so that the proximal end ofthe guide wire 170 is arranged so as to include an impact fitting toprotect the guide wire about the proximal end.

In the alternative embodiment, the guide sleeves 102 a are tubularmembers that are configured so that at least a portion 103 of each guidesleeve is arcuate. In the illustrated embodiment, the arcuate portion103 of the guide sleeve 102 a is proximal the vertebral body such thatone end of the arcuate portion comprises the distal end 108 of the guidesleeve that is in contact with the vertebral body 2. It is contemplated,however, that the guide sleeve can be configured so as to besubstantially arcuate between the vertebral body 2 and the cross member104.

The arcuate shape provides a convenient mechanism that can simplify theabove-described process for making an arcuate through hole 6 a in thevertebral body 2. The arcuate shape also provides a mechanism to orientthe tool, device or apparatus being inserted into the guide sleeves 102a, for example the drill or high energy source for forming the initialthrough hole, so use of the tool etc. is more convenient to the surgicalpersonnel performing the procedure.

After the arcuate through aperture 6 a is formed, then the implant 160is inserted therein so it is disposed within the through aperture 6 a inone vertebrae 2, passes or extends across the intervertebral space 4 anddisposed within the through aperture 6 a of the other vertebrae. Theimplant 160 is made from any one or more suitable materials such as e.g.a metal such as titanium or stainless steel, bone, bone with bonemorphogenic protein, carbon fiber composite, nitinol. The implant beinginserted into the final aperture is made from one or more of a metal(e.g., titanium or stainless steel), bone, morphogenic protein(including a combination of bone and bone morphogenic protein), carbonfiber composite, nitinol or biodegradable materials such as polyacticacid or polyglycolic acids and copolymers and other derivatives thereof,or collagen and collagen coated metal or bone. The implant also maycomprise an in situ-formed plug where the aperture acts as a mold for anepoxy or other polymer-based system. The implant, preferably is curvedso it generally conforms to the radius of the arcuate through apertures6 a in each vertebrae 2, however, other geometric shapes arecontemplated that are consistent with the intended use includingstraight members.

The implant 160 suitably can be provided with a circular or oval shape.The diameter or width of the implant can vary over a relatively broadrange and may depend on the size of the vertebrae and desired implantstiffness. More specifically, in preferred embodiments, the implant maysuitably range in diameter or width from about 5 mm or as small as ismechanically sufficient, to sizes approaching that of largeintramedullar rods, or about 22 mm. Preferably the implant should have adiameter or width from about 7 to 12 mm, more preferably about 9 mm. Theimplant also preferably should have an appropriate radius of curvaturesuch that both vertebrae are engaged while staying well clear of thespinal cord. That radius preferably is about 1.5 inches, as referencedfrom the arcuate implant's inner radius.

The implant 160 is suitably a solid or hollow (e.g., tubular) member.The implant can be suitably configured so as to have fenestrations 166(FIG. 6A) that allow biologic elements of bone to traverse through it oracross it, thereby enhancing potential for stability and forcross-segmental healing. In particular, the implant 160 can have cuttingfenestrations similar to a cheese grater, allowing fragments of bone tobe pared off as the implant 160 is being inserted into the throughapertures in either vertebrae. A fenestrated implant 160 that is hollowcan be filled with bone chips or synthetic or engineered bone healingmaterials, allowing for bone ingrowth, and a cheese grater type ofimplant with cutting fenestrations can add freshly pared fragments ofbone to the packed bone chips or other materials to enhance bonyingrowth. Additionally, the fenestrations 166 can be surface dimples,sharpened edges, cutting indentations or other alterations in theexterior surface of the implant 160 to enhance or further ensure thesecure fitting of the implant into the arcuate through aperture 6 a aswell as for facilitating bone growth.

The particular technique for inserting the implant 170 into the throughaperture 6 a of a vertebrae 2 for fixing of the movable segment isdependent upon the material used to make the implant. For an implant 160made from titanium, and as shown in FIG. 5A, a threaded end 162 (e.g., afemale threaded end) is provided at one end of the titanium implant 160for threaded engagement with the threaded counterpart (e.g., malecounterpart) at one end 172, the distal end of the guide wire 170. Thiscan be accomplished for example by removing at least one of the guidesleeves 102 from the entrance opening of one through aperture 6 a so thethreaded end 172 of the guide wire is exposed. The implant threaded end162 is then screwed onto the guide wire threaded end 172 and the sotethered end 162 of the implant 160 is positioned at the entranceopening of the through aperture 6 a and pulled into place by pulling on,for example, the proximal end 174 of the guide wire 170.

Preferably, the distal end 108 of one guide sleeve 102 remains engagedat the entrance opening for the other through aperture 6 a, so as toserve as a bearing surface or brace for the guide wire 170 as it isbeing pulled out of this entrance opening. This is done to keep theguide wire 170 from cutting through the cantellous bone when the guidewire is under tension because of the pulling action. Alternatively, atubular member with a rounded surface may be advanced over the guidewire and through the remaining guide sleeve 102, to ensure that theguide wire pulls from the appropriate angle. This technique is suitablefor use with metallic and other rigid material type of implants.

Alternatively, and as shown in FIG. 5B, a pushing mechanism is useablefor inserting or tamping the implant 160 into the arcuate throughapertures 6 a. In the illustrated embodiment, an arcuate pushingmechanism 300 is configured so as to rotate about an axis of rotationthat corresponds generally to the center of the circle subscribed by thearcuate through apertures 6 a. The arcuate pushing mechanism applies aforce to the distal end of the implant 160 so as to drive the proximalend of the implant through the arcuate through aperture 6 a in onevertebrae, across the intervertebral space 4 and into the arcuatethrough aperture 6 a of the other vertebrae 2.

In the illustrated embodiment, the positioning jig 100 is removed exceptfor the intervertebral spacing member 110 or bone interverterbral spacerwhere the intervertebral spacer 114 remains disposed in theintervertebral space 4. The arcuate pushing mechanism 300 is attached tothe end of the interconnecting member 112 by means of a jig or othermember or device so the pushing mechanism can rotate about the end ofthe interconnecting member. In this way, the arcuate arm 302 of thepushing mechanism 300 can be advanced by having one of the surgicalpersonnel rotating it about its axis of rotation. Alternatively, or inaddition, the surgical personnel can strike one end 304 of the arm 302with a mallet or other weighted object so as to drive the implant 160into the through aperture 6 a. For example, striking may be requirednear the end of the insertion process when there is maximum frictionbeing developed on the inserted implant. The arm 302 also may beconfigured with a curved support sleeve 306 in which the implant isreceived.

Although the implant 160 and through apertures 6 a are sized so thatthere is preferably at least a snug-fit therebetween, as an extrameasure of protection, the implant 160 may be further secured in placeat its ends by means of screws 400 as shown in FIG. 6C. Alternatively,the implant 160 may be secured in place by a plate, screw, staple or acombination thereof. Additionally, the implant can be arranged so as toinclude a biting or expansion element(s) that can be driven out in alateral direction so as to engage the bony structure of the vertebrae 2.

As provided above, and as shown in FIGS. 7A–B, the implant 160 a can bemade from nitinol. A nitinol implant 160 a is advantageous in that acurved nitinol implant can be straightened as shown in FIG. 7B prior toinsertion into the arcuate through apertures 6 a. The straightenednitinol implant 160 a can be advanced down one of the guide sleeves 102in any of a number of ways, for example, by pushing or pulling, so itcan be driven into the arcuate through apertures 6 a. The nitinolimplant 160 a also can be inserted into the arcuate through apertures 6a in any of the other fashions described above in connection with FIGS.5A–B.

Additionally, a sharp edge of the nitinol implant can be used like areamer or awl to thereby enlarge the initial through hole 6 as theimplant is being inserted or driven into the initial though aperture.This avoids the intermediate step of drilling or otherwise forming thearcuate through aperture 6 a before insertion of the implant.

FIG. 7C depicts an illustrative device 400 for inserting a nitinolimplant 160 a, which device includes a guide tube 402 and a pusher 404.The distal end 408 of the guide tube 402, similar to the positioning jigguide sleeve distal end 108 is preferably configured so as to be capableof releasably mating with a surface, or portion thereof, of thevertebrae 2 where the entrance of the arcuate through aperture 6 a islocated. In the illustrated embodiment, the guide tube distal end 408 isconfigured with a cut out so as to receive a corner of the vertebrae 2therein.

The distal end 408 is disposed on the vertebrae so that the lumentherein is aligned with the arcuate through aperture 6 a. Thestraightened nitinol implant 160 a is inserted into the guide tube 402along with the pusher 404 such that the distal end of the pusher is incontact with the proximal end of the nitinol implant. The pusher distalend 408 mates with the implant proximal end so as to maintain theorientation and direction of the nitinol implant 160 a within the guidetube 402 so that it curves in the proper direction when it exits theguide tube. Alternatively, and as shown in FIGS. 8A–B, the orientationof the nitinol implant 160 a within the guide tube 402 is maintainedwith a flat side or with a key and notch type of arrangement.

The pusher 404 includes a stop 406 to limit the travel of the pusherwithin the guide tube 402. This in turn limits the amount of travel bythe nitinol implant 160 a so as to assure that the implant remainsburied within the vertebrae and not exposed above the surface thereof.

The placement of the implant according to the systems and methods of thepresent invention is advantageous in that the inserted implant residescompletely within the vertebrae and, thus, within the spine, with noprotrusion as compared with prior art devices. The implant and itsplacement provide a configuration which allows for some compression andcantilever force, but deters rotation and sheer. Additionally, in thepresent device, the moment arm is more centrally located within thespine as compared to prior devices. This central location also providesbetter stability in the face of torsion as compared to prior artdevices.

In general, the placement of an arcuate implant within the arcuatethrough apertures as described herein is particularly advantageousbecause the implant is buried to avoid contact with neurovascularstructures. The placement provides load sharing and thus provides abetter healing bio-mechanical environment and also provides a moreadvantageous fixation to avoid mechanically sub-optimal stresses. Alsoimportant, this method allows securement and avoids displacement of aspinal fusion or disk replacement device without modification or damageto the vertebrae's load bearing surface. Rather, one or two holes placedin or around the center of a vertebrae can be sufficient. The method andpositioning jig 100 of the present invention also are advantageous inthat the jig can be adapted for use in minimally invasive procedures.Additionally, the capability to position implants in accordance with themethods described herein enables avoiding blood vessel injury, erosioninto organs and damage to adjacent nerves. This provides a significantadvantage over presently existing technologies for disorders of thespine including fractures, arthritis, deformity, infections, tumor andmechanical spinal disorders.

Although the foregoing method describes extending a single implantbetween adjacent vertebrae this description should not be construed asbeing a limitation as one or more implants can be positioned across eachmotion segment as described herein.

In addition, the above described method can be further adapted so as tobe used to secure an intravertebral prosthetic device 500 (i.e.,artificial disc) such as that shown in FIG. 6A. According to this aspectof the invention, the implant is made partly or wholly from a flexiblematerial such as silicon, elastomeric polymers, polyurethances andcopolymers thereof, hydrogels, collagen, bioabsorbables, compositions,or a metallic spring or coil, so as to allow continual mobility betweenthe vertebral bodies. One or more arcuate implants are provided whichpass through a partial or complete hole in the prosthesis. Thiseffectively prevents the prosthesis from becoming dislodged as well asmaintaining its location and orientation within the disc space.

There is shown in FIGS. 17A–C exemplary arcuate implants 160 b–d for usein securing the intravertebral prosthetic device 500 within the bones ofthe spine. Referring now to FIG. 17A, there is shown an arcuate implant160 b having a first section 163 disposed between two end or secondsections 165 that mechanically engage the first section. The firstsection 163 is made up of a compressible material and the secondsections 165 are made up of a material(s), such as metals and bone, thatis conducive to the attachment of the second sections to the bonethereby securing the implant 160 b. Alternatively, and as shown in FIG.17B, the implant 160 c can comprise a first section 163 that is bondedor otherwise mechanically secured to the second sections 165.

The implants 160 b, c of either FIGS. 17A, B extends through an apertureor hole in the prosthetic device 500 and into the vertebral bodiesadjacent to the prosthetic device similarly to that illustrated in FIG.16A. Additionally, the first section 163 of either of the two implants160 b,c is arranged so as to extend through the prosthetic device 500.See also the discussion above for FIG. 16A for other aspects of securingthe prosthetic device (e.g., one or more apertures in the prosthetic)and materials for the implant.

The above described method also can be further adapted so as to be usedto secure an intravertebral prosthetic device 500 (i.e., artificialdisc) according to another technique such as that shown in FIG. 6B usingan implant, such as the exemplary implant 160 d shown in FIG. 17C. Inthis technique any of the mechanisms and methods described herein areused to form at least an aperture 6, preferably an arcuate throughaperture, in one adjacent vertebral body 2 a. More particularly, theaperture forming mechanism or method also forms another aperture 6′ inthe other adjacent vertebral body 2 b. This another aperture 6′ in theother vertebral body 2 b is not a through aperture but rather onlyextends only into a portion of the other vertebral body. After formingthe apertures 6, 6′, the prosthetic device 500 is disposed in the discspace or intervertebral space 4. The implant 160 d is then pressed intoand through the aperture 6, through the prosthetic device 500 andintervertebral space 4 and into the aperture 6′ of the other adjacentvertebral body 2 b.

The exemplary arcuate implant 160 d shown in FIG. 17C includes a firstsection 163 and a single second section 165 that mechanically engagesthe first section as shown in FIG. 17A or is bonded or other wisemechanically secured to the first section as shown in FIG. 17B.Reference shall be made to the above discussion regarding FIGS. 17A,Bfor further details regarding the make up and materials of the first andsecond sections 163, 165 and the discussion for FIG. 16A for otheraspects of securing the prosthetic device (e.g., one or more aperturesin the prosthetic) and materials for the implant.

FIG. 9 shows a method for inserting an implant 600 according to a secondaspect of the present invention. A final through aperture 604 is formedin each of the vertebrae in accordance with above described techniquessuch as by drilling. Except that the through aperture 604 that receivesthe implant can be straight as shown in FIG. 9 or can be arcuate asshown in any of FIGS. 3–6. As such, reference should be made to theforegoing discussion for further details regarding the formation of thefinal through aperture 604.

In the method according to the second aspect, the implant is in twosections 602 a,b. The proximal ends 608 of the two sections 602 a,b areparticularly configured so they can be mated to each other andinterlocked to each other by means of an interference fit, a nut andbolt, a screw or a pin 606. Thus, to fix the moveable segment, onesection 602 a is inserted into the through aperture 604 in one vertebrae2 and the second section 602 b is inserted into the through aperture 604of the other vertebrae. The two sections 602 a, b are inserted intotheir respective through apertures until the proximal ends 608 thereofare mated to each other. The pin 606 or other securing mechanism is thenused to interlock the proximal ends and thus form a rigid implant.Although the sections are illustrated as being straight, it is withinthe scope of the present invention for the sections to arcuate so as toform an interlocking rod when assembled.

FIG. 10 shows a method for inserting an implant 600 according to a thirdaspect of the present invention. According to this method, the apertures702 in each vertebrae 2 are formed so they extend from the vertebralspace 4 outwards, penetrating into the cancellous bone. In this aspect,the apertures 704 formed in the vertebrae need not be through apertures.The implant 600 is like that described above for the second aspect ofthe present invention except that it is inverted from that shown in FIG.9.

There is respectively shown in FIGS. 11A, B a cutter bracket system 1100and a curved bit or drill system 1120, the curved drill system being foruse with such a cutter bracket system. The cutter bracket system 1100and curved drill system 1120 comprises another embodiment of the presentinvention for forming arcuate apertures 6 a (FIG. 6A) in each of theadjacent vertebral bodies 2. Referring now to FIG. 11A, the cutterbracket system includes temporary vertebral screws 1102, pivot brackets1104 and a pivot arm 1106. In the illustrated embodiment, there is twotemporary vertebral screws 1102 that are each secured to the adjacentvertebral body 2 that is to be fused, however, this shall not beconstrued as a limitation on the number of intervertebral screws.Extending from the temporary vertebral screws 1102 are the pivotbrackets 1104, which locate the pivot point 1108 with respect to theadjacent vertebral bodies 2 and maintian the pivot point in thisorientation. The pivot arm 1106 is rotatably mounted to the pivotbrackets 1104 using any of a number of mechanisms or techniques known inthe art so that the pivot arm pivots or rotates about the pivot point1108. In an exemplary embodiment, the temporary vertebral screws 1102,the pivot brackets 1104 and the pivot arm 1106 are made from stainlesssteel although other materials are contemplated.

The drill system illustrated in FIG. 11B includes a curved cannula 1122,a flexible cable 1124, a cutting head or burr 1126 and a motor 1130. Theflexible cable 1124 is rotatably disposed with the curved cannula 1122.One end of the flexible cable 1124 is attached to the cutting burr 1112and the other end of the flexible cable 1124 is attached to the motor1130, whereby the motor drives the cutting burr so it to rotates in thedesired manner. In the illustrated embodiment, the motor 1130 also ismounted to an end of the curved cannula 1122. In an exemplaryembodiment, the curved cannula 1122 is made from stainless steel and theflexible cable 1124 is a flexible, teflon coated stainless steel cable,the cutting burr 1126 is made from stainless steel, although it iswithin the scope of the present invention for other materials to beused.

The motor 1130 includes any of a number of devices known in the art thatdevelop or provide a rotary output which can be used to rotate theflexible cable 1124, such devices include, but are not limited to,electric or pneumatic drills, DC/AC electric motors, or, pneumatic, airdriven rotary motors. It also is within the scope of the presentinvention for the drill system 1120 to further include a couplingmember, as is known in the art, that operably and rotatablyinterconnects the flexible cable 1124 and the motor 1130 such that themotor is located remote from the curved cannula 1122. In this way, anyof a number of rotary devices such as a drill, that are readilyavailable, can be adapted for use in the drill system 1120 of thepresent invention and interconnected to the flexible cable 1124 by meansof the coupling member.

The drill system 1120 is mounted or attached to the pivot arm 1106,distal from the pivot point 1108, by means of a connector 1128 on thecurved cannula 1122. The connector 1128 and the corresponding feature onthe pivot arm 1106 comprises any of a number of mechanisms or devicesknown in the art (e.g., clamp type mechanism) by which the curvedcannula can be removably secured to the pivot arm so there isessentially no relative movement therebetween. In a particularembodiment, the curved cannula 1122 is secured proximal to or at thedistal end of the pivot arm. In this way when the drill system 1120 issecured to the cutter bracket pivot arm 1106 and the cutter bracketpivot arm 1106 is rotated about the pivot point 1108, the pivot armguides the curved drill system, in particular the cutting burr 1126 on awell-defined circular path.

In use, the cutter bracket system 1110 is temporarily secured to theadjacent vertebral bodies 2 to be fused by the temporary vertebralscrews 1102. In particular, the cutter bracket system 1110 is secured tothe vertebral bodies 2 so that the pivot point 1108 is positioned so asto be spaced from a surface of the vertebral bodies and so as to bebetween the adjacent vertebral bodies, more particularly at about themidpoint of the intervertebral space 4. After securing the cutterbracket system to the vertebral bodies the curved drill system 1120 ismounted to the pivot arm as described above.

The pivot arm 1106 is then rotated in one direction, for example aclockwise direction, about the pivot point 1108. As the pivot arm 1106is rotated thereabout, the cutting burr 1126 is operated so the drillsystem 1120 drills an arcuate hole in the vertebral body 2 on one sideof the pivot point. The curved drill is then remounted so the cuttingburr 1126 is on the other side of the pivot point 1108 and the pivot armis rotated in a counter clockwise direction so the drill system 1120drills an arcuate hole in the vertebral body 2 on the other side of thepivot point 1108. In an exemplary embodiment, the arcuate hole iscompletely formed when the pivot arm 1106 bottoms out or contacts thevertebrae being drilled. After forming the arcuate holes, the curveddrill system 1120 is dismounted from the pivot arm 1106 and the cutterbracket system 110 is disconnected from the adjacent vertebral bodies 2.In this way, two matched arcuate holes are formed in the adjacentvertebral bodies 2 that are sized and configured to receive an arcuateimplant being inserted therein. Reference shall be made to the foregoingdiscussion for further details regarding such an arcuate implant orfixation member.

Although the foregoing describes the formation of the arcuate holes orapertures 6 a in the adjacent vertebral bodies 2 using a curved drillsystem 1120 mounted to the pivot arm 1106, this shall not be construedas a limitation. As discussed hereinabove, it is within the scope of thepresent invention for other devices, mechanism or techniques, such asthe above-described ablation energy sources, to be adapted for use witha rotating pivot arm 1106 to form the through holes/apertures. As suchthese other devices, mechanisms or techniques are contemplated for usewith the above-described cutter bracket system.

In accordance to another method of the present invention, a slot is cutin each of the adjacent vertebral bodies and a biscuit implant isinserted into the slots so as to also bridge across the intervertebralspace 4. Preferably the slots are simultaneously cut in the vertebralbodies so a common channel is formed therein. In an exemplaryembodiment, and with reference to FIGS. 12A, B there is provided acutting device 1200 having a cutting implement, for example a circularblade 1206 that is rotated by a motor (not shown). The cutting device1200 also is configured so the blade 1206 is moveable between a firstposition, where the blade is disposed within the device housing 1202(FIG. 12A), and a second position, where a portion of the blade extendsoutwardly a predetermined distance from an exterior side 1204 of thehousing (FIG. 12B). Preferably, the exterior side 1204 from which theblade 1206 extends is configurable so that in one position the exteriorside is substantially parallel to a tangent at the midpoint of the bladeand further includes indicia 1208 representative of the mid-point of theblade.

In use, and as shown in FIG. 12C, the cutting device 1200 is positionedso the device housing exterior side 1204 abuts or is adjacent to thevertebral bodies 2 and so the indicia 1208 representative of the blademidpoint is pointing towards the intervertebral space 4, preferablyabout a midpoint between the adjacent vertebral bodies. The rotatingcircular-blade 1206 is then moved from the first to the second positionso as to simultaneously cut an arcuate slot in each of the adjacentvertebral bodies 2. After cutting the slot, the circular blade 1206 isreturned to the first position with the device housing 1202 and thecutting device 1200 is removed from the vertebral bodies.

As shown in FIG. 12D, after the arcuate slot 1209 is cut in the adjacentvertebrtal bodies 2, a biscuit implant 1210 a such as that shown in FIG.12F, is inserted into the arcuate slot in each of the adjacent vertebralbodies and so as to bridge therebetween. The biscuit implant 120 a issecured in the arcuate slot 1209 using any of the methods describedherein for the other implants of the present invention thereby fusingand stabilizing the adjacent vertebral bodies. Alternatively, a biscuitimplant 1210 b such as that shown in FIG. 12G, is configured so as toinclude a spacer element 1212. Thus, when the biscuit implant 1210 b isinserted into the arcuate slots 1209 the spacer element 1209 thereof isreceived and disposed in the intervertebral space 4 as shown in FIG.12E.

In addition to the exemplary biscuits implants 1210 a,b illustrated inFIGS. 12F–G, it is within the scope of the present invention for thebiscuit implant, whether it is configured with or without a spacerelement 1212, to be formed in any of a number of geometric shapes thatare otherwise consistent with the intended use. This includes thebiscuit implants 1210 c–f shown in FIGS. 12H–K. Reference shall be madeto the foregoing discussion regarding the other implants or fixationmembers of the present invention as to the materials and other features(e.g., fenestartions) which apply equally for a biscuit implantaccording to the present invention.

There is shown in FIGS. 13A–13F, an implant system according to thesesystems and methods. FIG. 13A shows an embodiment of the inner implant800 adapted for inspection within the outer implant 810 shown in FIG.13B. The inner implant 800 in FIG. 13A is shown as a substantiallyhollow device equipped with a fenestrated wall 802. The inner implant800 bears on a lateral surface 814 a key slat 804 adapted to secure andorient the inner implant 800 within the outer implant 810 shown in FIG.13B. Specifically, the key slat 804 in the illustrated embodiment canslide into a key groove 808 situated on the inner aspect 818 of theouter implant 810. In the embodiment shown in FIG. 5B, the outer implantis equipped with a trough and trough slit and a fenestrated wall 812 asshown in FIG. 13D. It is understood that the devices shown in thesefigures can be fabricated from a plurality of materials including bothabsorbable and non-absorbable biocompatible materials. Materials mayinclude metallics, ceramics, plastics, polymers, biological materialsand materials produced by biotechnology. A variety of suitable materialswill be readily envisioned by those of ordinary skill in the art for usein the system and methods of the present invention.

FIG. 13C shows a lateral view of two vertebral bodies 820 and 822showing the general position of the implant system 824. In more detail,the edge of the outer implant 828 is shown imbedded and buried in thevertebral bodies 820 and 822. The edge of the inner implant 830 is shownpositioned within the intervertebral disc space 834. A set of bone cuts832 and 836 are made at the buried end of the implant system 824. FIG.13D shows an anterior view of the outer implant 838 positioned with theinner implant 840 secured within it according to the systems and methodsof the present invention. FIG. 13E shows an anterior view of the innerimplant 844 secured within the outer implant 842 according to thesystems and methods of the present invention. In FIG. 13E, however, theentire implant system 845 is shown in the rotated 90 degrees relative tothe angle at which the implant system 848 is inserted into the vertebralbodies and disc space (not shown). The inner implant 844 in this viewassumes a vertical position within the implant system 848, and the outerimplant is rotated 90 degrees to effect this repositioning.

FIG. 13F shows in more detail a perspective view of an embodiment of theimplant system 850 according to the present invention. The inner implant854 is shown positioned within the outer implant 858, the entire implantsystem 850 being turned vertically. As a consequence of thisrepositioning, two bone sections 860 contained between the inner implant854 and the outer implant 858 are turned to a vertical position. Thesebone sections 860 thus provide structural stability to the system 850and to a spine unit (not shown). The vertical repositioning placescortical bone in a more supportive position.

In the illustrated embodiment, the outer implant 858 is shown with afenestrated wall 852 for facilitating bony ingrowth. These fenestrationsare larger at the upper and lower confines of the repositioned bonegraft sites to enhance fusion. Also in the illustratred embodiment, theinner implant 854 is shown with a hollow interior section 862 availablefor containing a solid displacing shim and bone chips, bone matrices,growth factors or other agents for encouraging or facilitating bonyingrowth and enhancing stable positioning of the verticalized corticalbone sections. Other substances useful to the healing process can beprovided within this interior section 862. For example, antibiotics canbe placed in this interior section 862 in a suitable vehicle. Othersubstances and matrices can be envisioned by practitioners of those artsthat will fall within the scope of the present invention.

In more specific embodiments, the outer implant 838, 858 is configuredso as to include an axially extending slot or slit 841, 864 that isarranged and configured so as to permit adjustment of the diameter ofthe outer implant, for example to permit the outer implant to beexpanded outwardly. Thus, bone sections can be placed with as tight apositioning as possible and the outer implant 838, 858 can be placed infirmer or closer engagement with the vertebral bodies 820, 822. Thestructure forming the adjustment slit 841, 864 includes any of a numberof configurations, structures or arrangements that permit relativemovement between the sides of the outer implant on either side of theadjustment slit. Such structures, arrangements and configurationsinclude, but are not limited to an axially extending through aperture oran axially extending ship-lap type of joint where portions of theaxially extending sides slidably overlap each other.

There is generally down in FIGS. 14A–14C, an inner tool 900 to be usedaccording to the systems and methods of the present invention. FIG. 14Ashows the inner tool 900 positioned with the intervertebral disc space906. The inner tool 900 bears on its distal end, a shorter disc end 902that is adapted for insertion within the intervertebral disc space 906to allow for cutting a segment of the vertebral bodies 904 and 908 aboveand below it. FIG. 14B shows a perspective view of an inner tool 910according to the systems and methods of the present invention. Thedistal end 912 thereof is adapted for cutting the cortical vertebral endplates that it abuts. FIG. 14C shows in more detail an embodiment of thecutting mechanism bone by the inner tool 916. A cutting end 914 at thedistal end of the tool 916 bears a set of stop cut blades shown here inthe retracted position 920 and in the extended position 918. Directingthe blades from the retracted position 920 to the extended position 918effects a cut in the adjacent bone (vertebral endplate, not shown).While the depicted embodiment of a tool can be advantageously employedin conjunction with the implant system according to these systems andmethods other tools and devices can be envisioned by skilledpractitioners of these arts for cutting bone and for positioning animplant system all modification that fall within the scope of thepresent invention.

FIG. 15 shows a lateral view of an embodiment of the tool system 1000according to the present invention positioned in relation to thevertebral bodies 1014 and 1018. In this view an inner tool 1002 is shownwith its distal end positioned between the vertebral bodies 1014 and1018. An outer tool 1004 is shown in two positions, a position 1008before driving it into the vertebral bodies 1014 and 1018 and a position1020 after driving it into the vertebral bodies 1014 and 1018. A blade1022 of the outer tool 1004 is shown positioned at the anterior aspectof the vertebral body 1014 before the outer tool 1004 is driven into thevertebral body 1014. In this position 1020 after driving the tool 1004into the vertebral body 1018, the blade 1024 is shown imbedded in thevertebral body 1018, having cut it perpendicular to its anterior face.The inner tool 1002 can make bone cuts 1012 at right angles to the blade1024 of the outer tool 1004, thereby creating a bone slab 1010 that canbe repositioned according to the systems and methods of the presentinvention. This bone slab 1010 (section) can be cut so as to allow foranterior vertebral distraction by making these slabs oblong rather thancircular.

It should be clear that the methods, systems, and devices of theinvention are not limited to securing a pair of vertebrae, but ratherany combination of multiple vertebrae segments. It also should be clearthat the methods, systems, and devices are in no way limited tovertebrae segments. In particular, the invention enables securing anysolid substrates, particularly bone substrates, without use ofprotruding screws or plates. In this regard, FIG. 16 shows abone-to-bone application using techniques of the invention. It alsoshould be understood that the invention is applicable to a wide varietyof fixation configurations, including bone-to-bone with a gap;bone-to-bone without a gap; bone-to-bone with bony spacers; andbone-to-bone with a non-bony spacer such as a metal, polymer, or abiodegradable material.

Although a preferred embodiment of the invention has been describedusing specific terms, such description is for illustrative purposesonly, and it is to be understood that changes and variations may be madewithout departing from the spirit or scope of the following claims.

1. A spinal intravertebral prosthetic system, comprising: an intravertebral prosthetic device; an arcuate implant member of a size sufficient to extend between two adjacent vertebrate; wherein the intravertebral prosthetic device is configured to receive therein a portion of the arcuate implant member; and wherein the portion of the arcuate implant member that passes through the intravertebral prosthetic device is made from a compressible material.
 2. The spinal intravertebral prosthetic system of claim 1 wherein the compressible material is one of silicon, elastomeric polymers, polyurethances and copolymers thereof, hydrogels, collagen, bioabsorbables, compositions, a metallic spring or coil, or a material that allows continual mobility between the vertebral bodies.
 3. The spinal intravertebral prosthetic system of claim 2 wherein the intravertebral prosthetic device comprises a compressible material.
 4. The spinal intravertebral prosthetic system of claim 3 wherein the compressible material is one of silicon, elastomeric polymers, polyurethanes and copolymers thereof, hydrogels, collagen or bioabsorbables.
 5. The spinal intravertebral prosthetic system of claim 1, wherein the implant includes a non-flexible portion made of a material conducive to attachment to the vertebrae.
 6. The spinal intravertebral prosthetic system of claim 5, wherein the non-flexible portion of the implant is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 7. The spinal intravertebral prosthetic system of claim 1, wherein the compressible portion of the implant is disposed between end sections, each end section being made of non-flexible material conducive to attachment to the vertebrae.
 8. The spinal intravertebral prosthetic system of claim 7, wherein the non-flexible material is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 9. A spinal intravertebral prosthetic device kit comprising: an intravertebral prosthetic device; an arcuate fixation member; wherein the intravertebral prosthetic device is configured to receive therein a portion of the arcuate fixation member; and wherein the portion of the fixation member that passes through the intravertebral prosthetic device, is made from a compressible material.
 10. The implantable spinal intravertebral prosthetic device kit of claim 9, wherein the arcuate fixation member is configured to also extend through a preformed aperture in each of the two adjacent vertebrae.
 11. A spinal intravertebral prosthetic device kit comprising: a positioning apparatus including: two guide sleeves, each guide sleeve having a long axis, a cross member, an intravertebral spacer, wherein the guide sleeves are pivotably mounted to the cross member, and wherein the intravertebral spacer is spaced from the cross member and interconnected thereto so as to be between the pivots points for the guide sleeves; an intravertebral prosthetic device; a fixation member; and wherein a portion of the fixation member, passing through the intravertebral prosthetic device is made from a compressible material.
 12. The spinal intravertebral prosthetic device kit of claim 11 wherein the compressible material is one of silicon, elastomeric polymers, polyurethances and copolymers thereof, hydrogels, collagen, bioabsorbables, compositions, a metallic spring or coil, or a material that allows continual mobility between the vertebral bodies.
 13. The spinal intravertebral prosthetic device kit of claim 12 wherein the intravertebral prosthetic device comprises a compressible material.
 14. The spinal intravertebral prosthetic device kit of claim 13 wherein the compressible material is one of silicon, elastomeric polymers, polyurethanes and copolymers thereof, hydrogels, collagen or bioabsorbables.
 15. The spinal intravertebral prosthetic device kit of claim 11, wherein the fixation member includes a non-flexible portion made of a material conducive to attachment to the vertebrae.
 16. The spinal intravertebral prosthetic device kit of claim 15, wherein the non-flexible portion is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collogen or collagen coated metal or bone.
 17. The spinal intravertebral prosthetic device kit of claim 11, wherein the compressible portion of the fixation member is disposed between end sections, each end section being made of non-flexible material conducive to attachment to the vertebrae.
 18. The spinal intravertebral prosthetic device kit of claim 17, wherein the non-flexible material is one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 19. The spinal intravertebral prosthetic device kit of claim 11, wherein the fixation member is arcuate.
 20. A spinal system comprising: an arcuate member and an intravertebral prosthetic device that are capable of being surgically implanted in a mammalian spine; wherein the arcuate member extends between two adjacent vertebrae when implanted, wherein the intravertebral prosthetic device is configured to receive therein a portion of the arcuate implant member; wherein the arcuate member is configured so as to extend through a preformed aperture in each of the two adjacent vertebrae; and wherein the portion of the arcuate implant member that passes through the intravertebral prosthetic device is made from a compressible material.
 21. The spinal system of claim 20, wherein the intravertebral prosthetic device comprises a compressible material.
 22. An implantable spinal intravertebral prosthetic system, comprising: an intravertebral prosthetic device; an arcuate implant member of a size sufficient to extend between two adjacent vertebrae; wherein the intravertebral prosthetic device is configured to receive therein a portion of the arcuate implant member; wherein the implant member is sized so as to extend through a pre-formed aperture in each of the two adjacent vertebrae; and wherein the arcuate implant member is configured so as to have a uniform outer diameter.
 23. The implantable spinal intravertebral prosthetic system of claim 22, wherein the preformed aperture in each of the adjacent vertebrae is of a constant radius and wherein the arcuate implant member is configured so as to extend through each constant radius preformed aperture.
 24. The implantable spinal intravertebral prosthetic system of claim 22, wherein the arcuate implant member is configured so as to be secured by fixation points within the adjacent vertebrae.
 25. The implantable spinal intravertebral prosthetic system of claim 22, wherein the arcuate implant member is configured and sized so as to be a load bearing member.
 26. An implantable spinal intravertebral prosthetic system, comprising: an intravertebral prosthetic device; an arcuate implant member of a size sufficient to extend between two adjacent vertebrae; wherein the intravertebral prosthetic device is configured to receive therein a portion of the arcuate implant member; wherein the implant member is sized so as to extend through a pre-formed aperture in each of the two adjacent vertebrae; and a plurality of securing mechanisms one for each of the adjacent vertebrae, each securing mechanism being configured so as to secure the securing mechanism to one of the adjacent vertebrae, wherein the arcuate implant member is configured so as to be secured to each of the adjacent vertebrae by the plurality of securing mechanisms.
 27. The implantable spinal intravertebral prosthetic system of claim 26, wherein each end portion of the arcuate implant member is configured so as to be secured respectively to one of the adjacent vertebrae by one of the plurality of securing mechanisms, thereby further securing the arcuate implant member to the adjacent vertebrae.
 28. An implantable spinal intravertebral prosthetic system, comprising: an intravertebral prosthetic device; an arcuate implant member of a size sufficient to extend between two adjacent vertebrate vertebrae; wherein the intravertebral prosthetic device is configured to receive therein a portion of the arcuate implant member; wherein the implant member is sized so as to extend through a pre-formed aperture in each of the two adjacent vertebrae; and wherein the portion of the arcuate implant member that is received in the intravertebral prosthetic device, is made from a compressible material.
 29. The implantable spinal intravertebral prosthetic system of claim 28 wherein the intravertebral prosthetic device comprises a compressible material.
 30. An implantable spinal intravertebral prosthetic system, comprising: an intravertebral prosthetic device; an arcuate implant member of a size sufficient to extend between two adjacent vertebrate; a plurality of securing mechanisms one for each of the adjacent vertebrae, each securing mechanism being configured so as to secure the securing mechanism to one of the adjacent vertebrae; wherein the intravertebral prosthetic device is configured to receive therein a portion of the arcuate implant member; and wherein each of the plurality of securing mechanisms is configured so as to mechanically engage separate portions of the arcuate implant member, thereby securing the arcuate implant member to each of the adjacent vertebrae.
 31. The implantable spinal intravertebral prosthetic system of claim 30, wherein the arcuate implant member is sized so as to extend through a pre-formed aperture in each of the two adjacent vertebrae.
 32. The implantable spinal intravertebral prosthetic system of claim 30, wherein each of the plurality of securing mechanisms are configured so as to be threadably secured respectively in one of the adjacent vertebrae.
 33. The implantable spinal intravertebral prosthetic system of claim 30, wherein the portion of the arcuate implant member that passes through the intravertebral prosthetic device, is made from a compressible material.
 34. The implantable spinal intravertebral prosthetic system of claim 33 wherein the intravertebral prosthetic device comprises a compressible material.
 35. A method for securing an intravertebral prosthetic device between vertebrae, comprising the steps of: implanting an arcuate fixation member between the vertebrae, where each end of the fixation member is secured to one of the vertebrae; and passing a portion of the arcuate fixation member through the intravertebral prosthetic device, wherein at least the portion of the fixation member that is passing through the intravertebral prosthetic device is made from a compressible material.
 36. A method for securing an intravertebral prosthetic device between adjacent vertebrae, comprising: implanting an arcuate fixation member between the vertebrae; passing a portion of the arcuate fixation member through the intravertebral prosthetic device; wherein a portion of the fixation member is made from a compressible material; and wherein the fixation member is implanted through a preformed aperture in each of the adjacent vertebrae.
 37. The method of claim 36 wherein the pre-formed aperture in one of the adjacent vertebrae is a partially pre-formed aperture.
 38. The method of claim 36 wherein the preformed aperture has been drilled in each of the adjacent vertebrae.
 39. The method of claim 36 wherein the fixation member is the sole apparatus employed to maintain the location and orientation of the intravertebral prosthetic device.
 40. The method of claim 36 wherein the compressible material is one of silicon, elastomeric polymers, polyurethances and copolymers thereof, hydrogels, collagen, bioabsorbables, compositions, a metallic spring or coil, or a material that allows continual mobility between the vertebral bodies.
 41. The method of claim 40 wherein the intravertebral prosthetic device comprises a compressible material.
 42. The method of claim 41 wherein the compressible material is one of silicon, elastomeric polymers, polyurethanes and copolymers thereof, hydrogels, collagen or bioabsorbables.
 43. The method of claim 36, wherein the fixation member includes a non-flexible portion made of a material conducive to attachment to the vertebrae.
 44. The method of claim 43, wherein the non-flexible portion of the fixation member is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 45. The method of claim 36, wherein the compressible portion of the fixation member is disposed between end sections, each end section being made of non-flexible material conducive to attachment to the vertebrae.
 46. The method of claim 45, wherein the non-flexible material is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 47. The method of claim 36 wherein the fixation member is one of solid, hollow or with ingrowth fenestrations and screw holes or expansion bolts or staples.
 48. A method for securing an intravertebral prosthetic device of a spine, comprising: providing a positioning apparatus including two guide sleeves, each guide sleeve having a long axis; locating the two guide sleeves with respect to the adjacent vertebrae such that a vertex formed by the long axis of each guide sleeve is located in the intervertebral space of the adjacent vertebrae; forming an aperture in each of the adjacent vertebrae using at least one of the guide sleeves; inserting an implant into the apertures formed in each of the adjacent vertebrae so that the implant extends between the adjacent vertebrae and through the intervertebral space and so a portion of the implant passes through the intravertebral prosthetic device, wherein the portion of the implant is made from a compressible material.
 49. The method of claim 48 wherein said step of forming includes forming an arcuate aperture in each of the adjacent vertebrae such that the arcuate apertures in the adjacent vertebrae have a common axis of rotation.
 50. The method of claim 48 wherein the implant is inserted through a through aperture in one of the adjacent vertebrae and in a partially formed aperture in the other of the adjacent vertebrae.
 51. The method of claim 48 wherein the implant is the sole apparatus employed to maintain the location and orientation of the intravertebral prosthetic device.
 52. The method of claim 48 wherein the compressible material is one of silicon, elastomeric polymers, polyurethances and copolymers thereof, hydrogels, collagen, bioabsorbables, compositions, a metallic spring or coil, or a material that allows continual mobility between the vertebral bodies.
 53. The method of claim 52 wherein the intravertebral prosthetic device comprises a compressible material.
 54. The method of claim 53 wherein the compressible material is one of silicon, elastomeric polymers, polyurethanes and copolymers thereof, hydrogels, collagen or bioabsorbables.
 55. The method of claim 48, wherein the implant includes a non-flexible portion made of a material conducive to attachment to the vertebrae.
 56. The method of claim 55, wherein the non-flexible portion of the implant is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 57. The method of claim 48, wherein the compressible portion of the implant is disposed between end sections, each end section being made of non-flexible material conducive to attachment to the vertebrae.
 58. The method of claim 57, wherein the non-flexible material is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 59. The method of claim 48 wherein the step of inserting includes: inserting a beginning end of the implant into an entrance opening of one of the adjacent vertebrae; applying a force to the portion of the implant extending from the entrance opening so as to drive the implant beginning end though the aperture in the aperture of said one of the adjacent vertebrae, through the intervertebral space and into the aperture in the other of the adjacent vertebrae.
 60. A method for securing an intravertebral prosthetic device, comprising: providing a positioning apparatus including a pivot arm that is rotatable about a pivot point; locating the positioning apparatus with respect to the adjacent vertebrae such that the pivot point is disposed between the adjacent vertebrae; forming an aperture in each of the adjacent vertebrae responsive to rotation of the pivot arm about the pivot point, one of the apertures being formed is a through aperture; and inserting an implant into the apertures formed in each of the adjacent vertebrae so that the implant extends between the adjacent vertebrae and through the intervertebral space and passes through a portion of the intravertebral prosthetic device, wherein a portion of the fixation member is made from a compressible material.
 61. The method of claim 60 wherein said aperture in each of the adjacent vertebrae is arcuate.
 62. The method of claim 60 wherein the compressible material is one of silicon, elastomeric polymers, polyurethances and copolymers thereof, hydrogels, collagen, bioabsorbables, compositions, a metallic spring or coil, or a material that allows continual mobility between the vertebral bodies.
 63. The method of claim 62 wherein the intravertebral prosthetic device comprises a compressible material.
 64. The method of claim 63 wherein the compressible material is one of silicon, elastomeric polymers, polyurethanes and copolymers thereof, hydrogels, collagen or bioabsorbables.
 65. The method of claim 60, wherein the implant includes a non-flexible portion made of a material conducive to attachment to the vertebrae.
 66. The method of claim 65, wherein the non-flexible portion of the implant is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 67. The method of claim 60, wherein the compressible portion of the implant is disposed between end sections, each end section being made of non-flexible material conducive to attachment to the vertebrae.
 68. The method of claim 67, wherein the non-flexible material is made from one or more of a metal, bone, morphogenic protein, carbon fiber composite, nitinol, a biodegradable material, collagen or collagen coated metal or bone.
 69. The method of claim 60, wherein the step of forming includes forming by one of drilling or ablation of the bone by an energy source.
 70. The stabilizing method of claim 60 wherein the apparatus being provided further includes a drill that is affixed to the pivot arm such that when the pivot arm rotates about the pivot point the drill follows a defined arcuate cutting path.
 71. The method of claim 70 wherein the drill includes a curved drilling element.
 72. The method of claim 71 wherein the curved drilling element comprises a curved cannula, a flexible member disposed within the curved cannula, and a cutting burr affixed to an end of the flexible member, the flexible burr for cutting an arcuate aperture in each of the adjacent vertebrae.
 73. The method of claim 70 wherein the step of forming includes rotating the pivot arm so that a through aperture is formed in one of the adjacent vertebrae and so a partially formed aperture is formed in the other of the adjacent vertebrae.
 74. The method of claim 70 wherein the step of forming includes rotating the pivot arm so that a through aperture is formed in each of the adjacent vertebrae.
 75. A method for locating compressible material in an intravertebral space between vertebral endplates of a spine, said method comprising the steps of: creating an arcuate preformed aperture in a vertebral body that extends through the vertebral endplate of the spine; placing compressible material though the preformed aperture such that the compressible material is disposed between the vertebral endplates; and filling at least a portion of the preformed aperture with an arcuate member of a non-compressible material. 